Need Help/Advice

[digitalsteve]

But he has a 12V system, so 3100W/12V = 258A.
With the one charge controller he can only get 1/4 of that, about 750W. Hopefully just due to a cloudy afternoon they were getting 100W
The batteries (400 Ah 6V connected 2s2p) would prefer 170A but allow a maximum of 250A

You really do need a nap!

More charge controllers would let him harvest more. Only so many ways to divide 10 panels evenly; maybe a different model charge controller could split it up better.

I'd like to re-orient panels to reduce the peak and increase the hours of good production, but the nice solid ground mount is already there.
With optimum multiple orientations, it would make the ideal 170A for several hours per day.

 

[Hedges]

A 12V, 830 Ah bank is 10 kWh. It will take at least 4 sunny days to recharge with your 3100 W PV array.

4 batteries, each 400 Ah 6V is 10 kWh.
3000W array on a summer's day gets 5+ hours effective sun, 15 kWh
Winter's day if 2 hours effective sun, 6 kWh

If the system had enough charge controllers, it would recharge in 0.7 to 2.0 days.

Because the charge controller is limited to 63A, 800 Ah at 12V of battery is going to take 13 hours.
Usually we would consider equivalent full sun hours, but pulling only 750 or 850W from a 3000W array, it would get a few more hours full output.
Probably 2 days, a bit longer in the winter.
That's assuming it starts showing 750W, not 100W.

Now I'm the one who needed a nap.

 

[digitalsteve]

If he wires batteries in series (would require a 24v inverter) then he can get about 1500 watts out of the system. So, either a second MPPT or a new inverter, which ever costs less. Personally I would go for the 24v solution. Or parallel up to 3 more MPPTs and get the up to the full capacity of the panels using the existing inverter :>).

 

[Steve_S]

North Sask is big, no mention what city is closest. Using Saskatoon (Central Sask) these are the angles. March & September are the Median Months for a Fixed Ground Mount which for Saskatoon is 38 degrees as shown.

Midnite has this tool to figure out optimal arrangements/configurations for your panels and IT WORKS WELL you only have to put in your panel specs and play with the config to see what will produce the most according to your panels & controller. These people KNOW their products.

You DO NOT NEED ANOTHER SCC ! Seriously ! 3kw of panel to 12V battery with a MIdnite 250 come on... The only item in the entire setup that I would change is the Inverter which I'd b looking at the Samlex EVO-3012 which is infinitely programable configurable and has built in ATS & AGS which can signal an Atkinson GCSM (Generator Control Start Module) to auto-start a genset and more....
The EVO 3012 : Samlex America -- Products

BUT with that being said, if an Inverter Upgrade is to happen, then to be Honest, a 24V config would be far better especially down the line, usage always increases because we humans like to add things to our lives. Most here could easily admit that Setup #1 fell short and resulted in an upgrade... I started with a 3000W Inverter & ended up with 4000W, I am NOT unique in this... ALSO OF NOTE... The Samlex EVO's are 90-94% Efficient pending on model, unlike MANY others which are mid 80% and THAT makes a difference too.

SOURCE: Solar Angle Calculator | Solar Panel Angle Calculator (solarelectricityhandbook.com)

 

[SolarQueen]

But he has a 12V system, so 3100W/12V = 258A.
With the one charge controller he can only get 1/4 of that, about 750W. Hopefully just due to a cloudy afternoon they were getting 100W
The batteries (400 Ah 6V connected 2s2p) would prefer 170A but allow a maximum of 250A

You really do need a nap!

More charge controllers would let him harvest more. Only so many ways to divide 10 panels evenly; maybe a different model charge controller could split it up better.

I literally just woke up at 4:30 in the morning and said, wait, he has a 12V system! I can't go back to sleep until I wrote this. Thanks for catching it before I did. Yes, this is your problem. Don't let my sleepy previous answers cloud your judgement of me, this is very important. You are only getting 1/4 of your panel's power. You need to get this installer to fix your problem immediately. That much power into the charge controller will likely eventually damage it as well. Is there a combiner box near the solar array that would allow you to turn off one of the breakers, so it is only getting double its rated power? If not, you need to disconnect it completely once the batteries are charged back up. There should be breakers before and after the charge controller. The installer is 100% responsible for this and should not be allowed to get away with it.

Possible solutions:
1. Rewire the batteries to be 24V, all 4 in series. This will require replacing the inverter with a 24V one. May be good opportunity to replace it with the EVO. You can then have 1 string of 5 into each of 2 charge controllers. A new set of PV wires would have to come back from the solar array.
2. Install 3 Classic 150 charge controllers with 96A output. I don't like this solution, but it would work. All of the PV wiring would have to change. Two with a string of 3 panels, one with a 2 strings of 2. This allows you to keep the battery bank at 12V and keep the inverter.
3. Get 4 more batteries and replace inverter with a 48V one. You can keep the solar array as is, one controller can handle it. (63A x 310W = 3024W array, 3100W is fine).
4. Disconnect 7 of the 10 panels and live with 930W instead of 3100W.

I'm sorry I didn't catch this earlier, I'm slipping. Now I'm going back to bed.

P.S. If your installer fights back and says we are wrong, send him to Midnite Solar's online calculator and he will see we are right. https://www.midnitesolar.com/sizingTool/index.php

 

[SolarQueen]

Midnite has this tool to figure out optimal arrangements/configurations for your panels and IT WORKS WELL you only have to put in your panel specs and play with the config to see what will produce the most according to your panels & controller. These people KNOW their products.

You DO NOT NEED ANOTHER SCC ! Seriously ! 3kw of panel to 12V battery with a MIdnite 250 come on... T

You are 100% wrong. The charge controller is rated by the output, the Classic 250 is rated at 63A out. If it was a 48V system, one controller could handle it. 3100W / 48V = 64A out. Fine. At 12V, it is 3100W / 12V = 258A out. Do you think a 63A charge controller is OK for that? I don't. Neither does Midnite.

 

[Ryang]

This has been such a great thread to follow.

I was going to ask Steve why he though another scc wasn’t necessary, but you’ve answer that for me solar queen.

I’m voting for going 24v and a new inverter. It really seems like the installer missed some basics here. Send him an email with a link to this thread

 

[Steve_S]

With that Midnite Tool you can play with the string sizing (# of panels) and number of strings which allows you to play with the numbers to maximize what you can produce for your setup. I personally do not believe in using 12V beyond a 2000W Inverter, there's just too much involved to make it work well for a long duration. What about 4 panels & 3 strings ? or 4 strings of 2 panels ? I didn't bother playing with it...

Also remember, he is in Canada like I am and everything costs a HEAP MORE up here !
Even when you look at a price on Amazon.COM and the exact same product on Aamazon.CA comes out to a higher price all in when converted to USD. It is actually, more often not cheaper to buy from the COM and pay the extra shipping etc to get it up here. I just bought a Regulated powersupply from COM to save $120 (after conversion to USD).

Sorry but most in the USA don't get that nor can appreciate it when suggesting things.

 

[SolarQueen]

With that Midnite Tool you can play with the string sizing (# of panels) and number of strings which allows you to play with the numbers to maximize what you can produce for your setup. I personally do not believe in using 12V beyond a 2000W Inverter, there's just too much involved to make it work well for a long duration. What about 4 panels & 3 strings ? or 4 strings of 2 panels ? I didn't bother playing with it...

Also remember, he is in Canada like I am and everything costs a HEAP MORE up here !
Even when you look at a price on Amazon.COM and the exact same product on Aamazon.CA comes out to a higher price all in when converted to USD. It is actually, more often not cheaper to buy from the COM and pay the extra shipping etc to get it up here. I just bought a Regulated powersupply from COM to save $120 (after conversion to USD).

Sorry but most in the USA don't get that nor can appreciate it when suggesting things.

Watts is watts, regardless how things are wired. 10 strings of 1 or 1 string of 10 are still 3100W. It makes absolutely no difference to the number of charge controllers needed. Cost has nothing to do with it. According to Midnite, he is limited to 878W of solar on one Classic 250, regardless how it is wired, or how much it costs. He has 3100W. It will take more equipment to use the whole array, which option he chooses determines what equipment. The only option that does not require buying equipment is disconnecting 7 of his 10 panels.

 

[upnorth]

Thanks so much for everyone’s input and suggestions- I really appreciate it!

But if I am being honest, I think I am more confused now than when I started. Lol.
Like I mentioned at the beginning I understand very little of the technical aspects.

I bought the solar from a local company and had a friend of mine install it who is an electrician based on the attached diagram from the guy who sold it to me. From what I gather it sounds like as it currently sits my system is limited to only 878 Watts, or just 3 panels. Disappointing for sure!
As Steve mentioned everything is much more expensive up here in Canada as it’s not as readily available.

So here is my new challenge for all of you very knowledgeable people....how can I get more use out of this system while putting out the least amount of money? Hook batteries up in series and try to exchange current inverter for a 24v one? Not even sure I would be able to do this? And buy another charge controller?

 

[Hedges]

Maybe the system was design to be 24V, and a 12V inverter was accidentally listed or ordered.
At 24V, the Classic 250 charge controller is good for about 1700 to 1800W.
3100W (STC) of panels might produce 2700W under actual conditions. That is just reasonably over-paneled, makes up for days and seasons of less sun.

If the two series strings of 5 PV panels were oriented differently, like 9:00 AM and 3:00 PM sun, then just about all power produced could be used. And battery charge rate would approach optimum more hours of the day (63A from charge controller, 85A target for battery).

Perhaps a modification of the ground mount could change angle of the panels in groups of 5. Different times of day difficult to do with those two rows of 5, and don't want to tilt toward cabin which would shade it. But could tilt 5 optimal for winter and 5 optimal for summer.

MidNite Solar Inc.

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

www.midnitesolar.com

I don't believe having all the panels connected as they are now will damage the SCC. They provide 200 Voc, about 160 Vmp, which is OK. (Midnight 250 allows 250 Voc)
They can deliver 15A, which the SCC could handle fine (Midnight can deliver 63A.)
They won't ever deliver 3000W. The most that comes out of Midnight to the battery is 63A x 15V or so, 945W.

Excess watts won't be dissipated in Midnight either; a "Buck" circuit simply turns on a transistor connecting 180V PV (and a paralleled capacitor) to battery through an inductor, waits until current rises to 60A (comes from capacitor not PV), then turns off transistor. 60A continues to flow through inductor (that's what inductors do) and through a diode to negative. The transistor is on for maybe 1 millisecond, off for 11 milliseconds. 15 A at 180V flows from PV panel to capacitor for 12 milliseconds. 60A at 15V flows to battery for 12 milliseconds. 60A at 180V flows from capacitor to inductor for 1 millisecond.

The only somewhat higher than normal stress is that transistor is switching between 15V and 180V at 60A. (most of transistor's power is dissipated during switching.) If used with a 48V battery where this PV array would be right sized, transistor would switch between 60V and 180V at 60A. With a 12V battery the power dissipation of the transistor is about 1/3 higher than with a 48V battery. Not a big deal.

 

[Hedges]

So here is my new challenge for all of you very knowledgeable people....how can I get more use out of this system while putting out the least amount of money? Hook batteries up in series and try to exchange current inverter for a 24v one? Not even sure I would be able to do this? And buy another charge controller?

Your batteries can be wired as 12V (like presently) or 24V.

If you replace the inverter with a 24V inverter, and keep just the one charge controller, you can get a bit over half the PV during full sun. We call this "over paneling", letting power production be clipped in the middle of a sunny day. During partially cloudy days or other seasons, clipping will be reduced; you'll still get the same 1700W peak.

If you keep the 12 inverter and add a charge controller (need wires from array so each charge controller has its own 5 panels), that works too.

But the 24V inverter is more attractive. You can get a higher wattage one, and you can get one with charger built in.

 

[SolarQueen]

The drawing from the seller shows 1 string of 5 panels going into a charge controller, x2. So I interpret that as do that twice, which means 2 sets of that, 1 string per charge controller. But the mistake is that he wired the batteries in the drawing as 12V, not 24V, and sold you a 12V inverter and only 1 charge controller. I suggest you call the seller, explain the problem, and tell him you want to exchange the 12V inverter for a 24V, and get a discounted price for a 2nd controller. That is what I would do to make it right if I sold a system based on a bad design I did.

Problem to describe to seller: The Midnite Classic 250 is capable of 63A output. At 12V, that is less than 3 panels. He sold you 10 panels and one controller. If you switch it to a 24V system, which you can easily do by rewiring the battery bank, you can use 5 panels per charge controller. You need to exchange the 12V inverter for a 24V inverter. Don't let him say he can't do it because it is used. It is used based on their mistake, not yours. They need to make it right.

 

[Hedges]

Are there 2 wires coming to the cabin (and charge controller) from the solar panel array? or 4 wires?
That is, where is the connection made to parallel the two series strings of 5 panels?

That could be a "Y" connector at the array, with only 2 wires (maybe plus a 3rd wire for ground). In that case, you will need to pull an additional pair of wires if you add a second charge controller.

It could be 4 wires all the way from array to charge controller (or a combiner box). In that case, just connect two to one charge controller, two to the second new charge controller.

The two charge controllers can be wired together on the battery side (both charge one battery bank)
They can't be connected to the same PV panel wires. Each SCC needs its own wires to its own PV panels.


Another option besides 24V inverter would be 48V inverter.
You probably don't want to do that because it requires doubling the number of batteries.
At 48V, the single Midnight Classic 250 would be just fine for your 3100W of PV panels.
(not likely what you want to do because batteries cost more than everything else. Just listing this option for completeness.)

 

[upnorth]

Here is an updated photo of display from about 20 minutes ago. Very cloudy day currently.

 

[upnorth]

I think they are only 2 wires coming from the solar array to the cabin. The combiner box is mounted on the array and then the 2 wires come into cabin from there.

From what everyone is saying I am guessing the best option would be to try and swap the 12v inverter for 24 volt inverter, preferably an Evo model so I could plug the generator into the inverter and this in turn would charge the batteries if needed? And I would need another midnite 250 combiner box?

If the system is left as is for now until I have everything sorted then will it charge all the batteries up but it will just take longer??

 

[SolarQueen]

I think they are only 2 wires coming from the solar array to the cabin. The combiner box is mounted on the array and then the 2 wires come into cabin from there.

From what everyone is saying I am guessing the best option would be to try and swap the 12v inverter for 24 volt inverter, preferably an Evo model so I could plug the generator into the inverter and this in turn would charge the batteries if needed? And I would need another midnite 250 combiner box?

If the system is left as is for now until I have everything sorted then will it charge all the batteries up but it will just take longer??

Interesting, very cloudy, so you are getting only 292W out of the 3100W array. It's good to be overpaneled on a cloudy day like today. I am curious what you get tomorrow when it is sunny. If you start seeing full output from the array, I would personally recommend turning off one of the breakers in the combiner box so you only have 1 string going into the controller. I'm sure Hedges will disagree and say leave it. Your choice.

With the second charge controller, you can still use the existing combiner box. Just remove the finger bus bar from the top of the breakers, and bring your 2 positive lines into the 2 charge controllers without combining them. Just PV to breaker to charge controller. This requires pulling a new positive line from the combiner box to the controller. I think you can use the existing negative wire from the combiner box negative bus bar for both controllers, but not 100% sure, I'm going to check with Midnite, standby for their answer. If not, you'd need to pull another one of them too. The good news is, the wire doesn't need to be as big as the wire already running, because they are carrying half the current, since you are not combining the two strings.

 

[Hedges]

I think they are only 2 wires coming from the solar array to the cabin. The combiner box is mounted on the array and then the 2 wires come into cabin from there.

From what everyone is saying I am guessing the best option would be to try and swap the 12v inverter for 24 volt inverter, preferably an Evo model so I could plug the generator into the inverter and this in turn would charge the batteries if needed? And I would need another midnite 250 combiner box?

If the system is left as is for now until I have everything sorted then will it charge all the batteries up but it will just take longer??

Charging 292W, 23A is an improvement over 100W. As you get sun it should keep charging. But at this rate it will take a week (300W x 5 hours = 1500 Wh/day, 7 days for 10,000 Wh

If you bring generator and charger that would speed things up.

Midnight 250 is a charge controller, not a combiner box.
To add a second Midnight 250, you will have to pull 2 more wires from the array. If there is conduit, should be easy enough. If direct burial, would require digging another trench.

Just having one Midnight 250 isn't so bad with 24V inverter. You'll get a most a bit over 50% of peak power from the array. It would be "over paneled", so you continue to get that peak 1700 to 1800W for more hours of the day, and more seasons.
If there is a way to tilt one string of 5 panels differently from the other string of 5, that will reduce the power lost (or not harvested) due to overpanelling.

Sure, shutting off one string on a sunny day as SolarQueen suggests is no harm, and reduces stress on the charge controller.
Getting 10% on a cloudy day is to be expected. I get 5% to 50% depending on how thick the cloud cover.

To pull wires, shoving a fishtape through is sometimes difficult. But (assuming you have conduit), there are already at least two wires in it. You can use one wire as a pulling line, pull it out while pulling three in. (If you like, pull one of those back out to pull the original one back in, rather than cutting another wire off another spool.) Just be sure to secure the wires together well so they don't pull apart. Spread the knots/twists for each wire apart so it isn't too thick. You can get wire pulling lubricant or any other water-based glycerin product if you happen to have something else available.

 

[upnorth]

Here is an updated screenshot from right now. Still cloudy I guess.

 

[SolarQueen]

Midnight 250 is a charge controller, not a combiner box.

When you are combining over 150V, you need the Midnite PV6-250 combiner to hold the higher voltage 300V breakers. He's probably referring to that. https://www.midnitesolar.com/produc...e=Combiners&productCat_ID=9&sortOrder=6&act=p